Effects of delayed ettringite formation on reinforced concrete structures

International audienceThe prediction and reassessment of mechanical behaviour of reinforced structures affected by delayed ettringite formation (DEF) is a major challenge for structure managers. Firstly, several experimental tests were performed in laboratory to study the influence of both uni and tri-axial reinforcements on DEF expansion. Strain decreases in reinforced directions were observed, proving that DEF expansion under restraint is anisotropic. Cracks were observed parallel to the restrained directions. No strain trans-fert occurs from restrained directions to other ones. Secondly, data provided by these results are used to fit a numerical finite element model taking into account both chemical and mechanical aspects of DEF. Finally, an element of a DEF damaged structure is modelled with the whole model and compared to on site observations